A large pan-tropical family of trees spread over the tropical belt of the continents of Asia, Africa and South America and the largest is the dipterocarpoideae which is distributed from India to South East Asia.
Mixed lowland dipterocarp forests are one of the major forested landscapes in SE Asia and are composed of a suite of species but dominated by the dipterocarps.

The dipterocarps were named  after the first described genus, Dipterocarpus. 
  • Dipterocarp describes a two winged seed
    • Dip = two and pteros = wing and carpus = fruit.
  • Not all dipterocarps have two winged seeds, for example Shorea foxworthyi has five wings.
  • The dipterocarpoideae is the largest family containing 13 genera and 475 species.
  • This group of trees have several species that break out and above the forest canopy and are commonly called emergent trees.
  • Emergent trees are dispersed in small groups across the forest canopy and typically are 40m or more in height and can reach in excess of 80m.
The dipterocarps are tropical hardwood trees and consequently form the basis of the tropical timber industry in many South East Asian countries.
Working from left to right, starting top left: Mixed dipterocarp canopy at FRIM, Malaysia,Mixed dipterocarp canopy at Danum valley, note the emergent trees in the back ground, view of a secondary forest at Danum valley, Shorea foxworthyi at FRIM, looking down the bole of a Vatica species at Fraser's Hill, Malaysia, Looking up at the rigging in a Parashorea species at Danum valley, seeds of S. foxworthyi, mixed seedling bank in the understory of primary forest, Danum valley, a masting Shorea species in 2010, Danum valley. 
The dipterocarps are a highly threaten group of trees across many of the countries they occupy and are particularly vulnerable in Malaysia and Indonesia.
The threat to dipterocarp trees comes from two main sources:
  • Logging and the timber industry
  • Land clearance and conversion to agriculture
In contemporary times the most significant threat is land conversion to Palm Oil production.
  • In 1990 there were about 3.5 million hectares of industrial oil palm spread across Malaysia, Indonesia and Papua New Guinea and by 2010 that area had increased to 13.1 million hectares.
  • Deforestation and land conversion still continues today.
  • The rate of deforestation and land conversion is one of the significant issues with the conservation of dipterocarp trees. This is because many of the dipterocarps are what we call masting species.
  • Masting species synchronise their flowering and fruiting to each other leading to a huge seed drop. This is an ecological strategy that has evolved over millions of years, which helps to satiate the ground dwelling herbivorous. 
  • The other major issue with conserving the dipterocarps is they often take 80+ years before they become reproductive and finally the seeds have no longevity in the soil seed bank, surviving only as a seedling bank.
The issues describe above are just an overview of the problem with deforestation and land conversion in S.E. Asia. It is all to easy to criticise these countries for these very damaging practices but we must remember in the UK we cleared much of our wooded landscape many 100's of years ago and indeed by 1066 the UK wooded landscape was 80% secondary forest and our oil palm equivalent is the wheat crop and intensive perennial rye-grass pasture.

Its  easy to get very pessimistic about the logging and land conversion in S.E.Asia but there are some excellent examples of conservation work occurring in the region and there are strategies to conserve the dipterocarps based on seedling banks, nurseries and enrichment planting. Explore the conservation of dipterocarp forests here.
Working from left to right, starting top left: Loading logged dipterocarps using heavy machinery, degraded forest coupe following 1970's logging. Here the ground has been so heavily compacted it is very difficult for seed recruitment to occur,mature oil palm, establishing a young oil palm plantation, aerial view of converted forest to oil palm, Sabah. The last two images are of a rubber plantation in Malaysia.

The diversity of dipterocarp forests:A SLIDE SHOW

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